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Upgrade Opinions

Spoke with Dana Caldwell today about having my Z8 shipped out to Peter Pan for upgrades. The questions that I have is addressed to those owners who have had the Quaife 364 diff and or the UUC short shifter installed. What do you think? Are you glad you did it? What did it cost? Was it worth the expense? Would you do it again? Any response is greatly appreciated. Dana ask that I forward him my laundry list of upgrades by June 1st. Thank you in advance.

Did both and am glad that I did, but I know that there are others who feel otherwise. When the time came for us to choose gearing in a group buy of the Quaife differentials, there were some who felt that the 3.64 brought second gear up too quickly. I appreciate the extra little kick, thought, which amounts to an approximate 10% increase in torque - a difference that can actually be noticed.
The short shifter also works well, though the quicker, shorter shifts come with the expense of more effort to shift.
I can't recall the costs, but I do recall that the Quaife differential was quite expensive. The LSD is probably more important than the gearing.

I did the Quaife, but left the final drive ratio the same, and the UUC short shift kit with the steel shifter knob. I really liked these upgrades, but they were both 'also rans' compared to the big ones, doing the Alpina suspension with the Dinan swaybars (use H&R if you can't get Dinan again). I also really like the Brembo big brake kit and the change to the larger wheels with the Michelin Pilot Sport 2's - though I'm trying the Pirelli's on my new set of rims as they are a bit wider at the rear, which looks much better on the rim.

Don't forget the CDV and the Rogue Engineering solid bushings for the transmission, and if you can find one get Dinan's Castor Plates to combine with your PP. I also did the Dinan software upgrade, and many owners have done, and love the Eisenmann exhaust. I'd been waiting to see if there would be a Dinan one after GM's car, if not then maybe the Supersprint system will be my choice, as it replaces the entire stock system.

I think that about covers it, but you can also add more power with Dinan's S2 package.

Andrew Macpherson

Expert Z8 Inspections, with full support for both Z8 sale and purchases.

I have the eisenmann exhaust, the Quaife as well as the upgraded 3.64 final drive (OEM is 3.38 I believe), Dinan sway bars, performance package, and bridgestone REO50A Pole Position tires which are not run flats. Also have the CDV removed.

I will rank these in the order of the biggest difference/ Improvement that I feel.

1. Performance Package- peace of mind.

2. tires- replace the run flats, they are terrible.

3. 3.64 gears- this will be a personal choice- I like it- its a little more torquey, the engine seems to rev quicker- its being forced to. If you do a lot of 6th gear cruising and you like having the revs as low as possible in 6th gear then Im not sure. I think most people would like this change.

4. CDV- you dont realize what youre missing with it in there. Btw- its gotten worse with the newer models- on the new M3 the CDV intervention makes clutch engagement very tricky IMHO.

5. Eisenmann race exhaust. I think it sounds amazing but Ive heard a few dissenting comments that say its a little too "american" sounding. It does not have that sound to my ears. Its very raspy and I think it lets you hear more of the cars natural sound.

6. the Quaife LSD. I really do not drive this car that hard I guess because I dont really get the LSD coming on very much. If I push it hard through a tight corner I can get it to engage but the cars personality, plus the high amount of grip from the tires already mean that my wanting this and objection to the open diff are really more academic than they are practical. This might be different for you. I will say it works great.

7. Dinan sway bars. IMHO they are totally useless unless you are going to make other changes to the suspension. Ive tried the Dinan bars in all their settings and I am back to the OEM from BMW configuration for stiffness. I believe it has to do with all of the suspension elements interaction- the stiffer I made the anti roll bars, the less the car would sit on its springs I believe and I didn't like how that felt in longer high speed bends- I want the car to settle down and it never quite did. So this is not the fault of Dinan- this is the fault of me not realizing that if you make a change to one thing, the odds are you will throw off something else. IMHO, if you do the suspension, get it tuned by someone who knows suspensions. I like how the car drives but if I didn't Id consider seeing if Mr. Dinan himself would be willing to do the work at his shop.

I know this will only throw confusion at you, and Jerry I don't mean to disagree with you, but I would honestly put the swaybars at the top of my list of upgrades - IMHO it is the best single change you can make to the car.

I've done this upgrade to all three of my Z8's and I feel that the change to the handling is enormous on the roads and tracks I've used my cars on. The bars remove the body roll, especially in fast transitions, both at the track and on twisty mountain roads. The car remains much flatter during cornering, allowing the suspension to remain uncompressed, and keep working, reducing the tendency to skip and slither that you get when the springs are over loaded. On several of fast mountain roads near me there are stretches with six or seven fast transitions that will leave the stock car feeling like a bouncing pendulum as the weight lurches from side to side if you try to flow thru them fast. With the swaybars it remains flat, unflustered and athletic by comparrison.

If your local roads are all big open flat-land roads then the swaybars may not make a huge difference, but if you are near the kind of endless twisty canyon and mountain roads both Steve Dinan and I are, then this upgrade is a must. It has one other huge added advantage, as I discovered on my first Z8 when I added my first set of bars - they totally remove passenger motion sickness on the twisties! That instantly allowed me to progress at a pace I enjoyed on the back roads I love without (so many) complaints from the better half! That alone may be sufficient reason to buy them, or the H&R's since the Dinan's are sold out in most areas.

Andrew Macpherson

Expert Z8 Inspections, with full support for both Z8 sale and purchases.

I just think the stock suspension needs more changed if you start messing with any one element of it. That's just MHO. Btw-i have one of the most motion sensitive passengers in the world and she never had one problem with the stock setup. I think the stock setup is not great for the track so my feeling is if one wants to so sway bars, they should really consider making other changes too. My roads are of the big sweeping highway kind and tight off ramps.

That certainly explains both your lack on need for the kind of transitional stability the sways really give the car, and also why your right side riders aren't getting motion sickness.

On the roads I love to fly along out here the loads are constantly changing, left, right, left, right at between 50-90mph, and the tires are getting worked very hard. The change in handling along one of my favorite local roads was literally night and day. What I originally said I still feel today.

Just north of the sprawl of LA is the Angeles Crest Highway (Route 2 - map below). It is one of the very best roads I know of. It is 58 miles long, and the longest straight anywhere in it's endlessly serpentine course is about three football fields long. All it will take is one drive with and without the stiffer sways, and you'll be a believer too!

Andrew Macpherson

Expert Z8 Inspections, with full support for both Z8 sale and purchases.

Not to change the discussion regarding the suspension, talked to Matt at Peter Pan on Thursday afternoon regarding my "wish list" of upgrades that Dana and I have discussed. Dana directed me to Matt to discuss the upgrade options. He asked me what "Diff Ratio" I was interested in. Honestly - I have not a clue. I never plan on tracking the Z as I have a M Coupe for that hobby. My office is 1 mile from my house and I have my own privite parking spot right outside my office window. I plan on using the Z as my daily driver and taking my son to school. So the ratio for the diff??? again - NOT A CLUE!!

In a nutshell the OEM is 3.38, and will give you a more touring feel, with slightly better mileage, while the the 3.64 will give you better acceleration and a sportier feel by lowering the overall gearing. This spins the motor around 8% faster at any given revs/gear combo if I remember correctly, but it increases the torque by a far greater percentage, though I can't remember the amount/reason/equation for this. You may also use a bit more gas.

You can read a full overview of the upgrade here. Everyone who has done it is very, very happy with it. I'm about the only person who did it leaving the stock ratio as I really like the way the car's gearing feels on the roads I use it on. I honestly never noticed the difference between the LSD and the open diff with the stock 3.38 ratio, and that includes tracking both at Buttonwillow, a very tight and technical track here in SoCal, so I'd suggest it isn't worth bothering with the LSD unless you plan to do the 3.64 ratio.

Andrew Macpherson

Expert Z8 Inspections, with full support for both Z8 sale and purchases.

3.38 is the standard ratio on the car. 3.64 is a typical one used as a modification. Its 8% more torque. At least Andrew and I agree about the ratios. On my roads I want the car to sit down on its suspension so I can take long turns and feel stable, with different stiffness the car either felt like it was too twitchy- reduced understeer- and it also felt like it would bounce too much on its springs. This brings up another thing about the suspension, I found when I added stiffness to the rear, the understeer was removed but the car wanted to change direction too easily and the place in the steering where this occurred felt less natural to me. I like the steering weighting up more linearly and this was altered also.

The two must haves IMO are the cross brace for the front engine compartment (just to make you feel secure about this issue) and most importantly the 364 Limited Slip differential. The latter absolutely transforms the car. With this mod, the Z8 feels like a race car, feels like it should feel. Instead of having kind of a cruiser sense in gear shifting, always seemingly stuck between gears, the car now rages in Ferrari territory. Acceleration is substantially better, torque is better. It becomes a real beast. I have the Quaife with the 364 sourced from the 7 series. I also think the suggestion of sway bars to be a very good one although I have not done this. One thing to remember is that the Z8 has been called one of the most collectible BMW's ever made. To this end, the collectors like their cars close to stock. The gear change is fine, but I for one would not do anything that cuts the car up (exhaust etc.)

To this end, the collectors like their cars close to stock. The gear change is fine, but I for one would not do anything that cuts the car up (exhaust etc.)

This is certainly something I expect to find more and more as time goes on, but I've always thought that 'correct' upgrades should be fine, and with the information available in places like this I think that a car with correct contemporary upgrades will retain equal value over the long haul. Most importantly of all, it has to drive the way you like during the time that you have it, so to that end I say do whatever you want so long as it is invisible, with the exception of wheels and brakes. I never liked the OEM brakes, but I really like my Brembos, and honestly think the car should have had them as stock, along with the LSD.

Andrew Macpherson

Expert Z8 Inspections, with full support for both Z8 sale and purchases.

I think extremely well defined contemporary upgrades would be exceptable in a car like this, however I would keep all original parts if any upgrades were completed. This is very important when modified cars show up at auctions. Also, any upgrade that modified any metal or plastic component, I personally would stay away from. Because historically, a collector car has always been worth more if its 100% original, and that doesn't mean just OEM parts, but as built. So like they say, there is only one chance to keep a car in that condition and once it is gone - it is gone.